Field
The disclosed embodiments relate to techniques for facilitating the operation of power adapters in hiccup mode. More specifically, the disclosed embodiments relate to bleeder circuitry for increasing leakage current during hiccup modes of power adapters.
Related Art
Rechargeable batteries are presently used to provide power to a wide variety of portable electronic devices, including laptop computers, tablet computers, mobile phones, personal digital assistants (PDAs), digital music players, and cordless power tools. The most commonly used type of rechargeable battery is a lithium battery, which can include a lithium-ion or a lithium-polymer battery.
During operation, a portable electronic device may be connected to a power adapter that converts alternating current (AC) mains electricity into direct current (DC) and/or a voltage compatible with the battery and/or components of the portable electronic device. Power from the power adapter may then be used to charge the battery and/or supply power to components in the portable electronic device. In the absence of the power adapter and/or mains electricity, the portable electronic device may be powered by the battery until the battery is fully discharged.
To prevent no-load power consumption by the power adapter, the power adapter may switch off if the portable electronic device is disconnected from the power adapter. Before switching off, the power adapter may use a hiccup mode to detect if the portable electronic device is connected to the power adapter or not. For example, the power adapter may operate in hiccup mode whenever the portable electronic device draws a small amount of power, such as when the portable electronic device is in a sleep mode and the battery of the portable electronic device is fully charged.
During the hiccup mode, the power adapter may periodically open a switch that disconnects the power adapter from mains electricity and monitor the subsequent voltage drop in the power adapter's voltage. If the voltage drops quickly, the power adapter may determine that the portable electronic device is connected to the power adapter and continue supplying power to the portable electronic device. If the voltage drops slowly, the power adapter may determine that the portable electronic device is not connected to the power adapter and switch off to prevent components in the power adapter from unnecessarily drawing mains electricity while the power adapter is not being used to supply power to the portable electronic device.
However, the hiccup mode may interfere with the operation and/or use of other components associated with the portable electronic device and/or power adapter. For example, the portable electronic device may be connected to the power adapter using a MagSafe (MagSafe™ is a registered trademark of Apple Inc.) connector that includes a set of light-emitting diodes (LEDs) indicating the charging and/or fully charged state of the portable electronic device. During the hiccup mode, the LEDs may turn off after the voltage in the power adapter drops below a pre-specified threshold. If the hiccup time of the hiccup mode extends past a certain point, the LEDs may flicker visibly, which may negatively impact the user experience with the portable electronic device.
Hence, what is needed is a mechanism for reducing hiccup times of hiccup modes in power adapters.